Process of densifying concrete structures



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ATTORNEYS INVENTOR BYLous S Vrtz L. S. WERTZ PRocEss oF DENSIFYING CONCRETE STRUCTURES ,1, wl/f Filed March l0, 1958 Jan. 21, 1941.

Patented Jan.A 21, 1941 PATENT 'OFFICE raocsss or nnusirrmc coNcns'rs smucrunns v Louis S. Wiertz, Shaker Heilhtl, 0h10 Application Match 10, 1938. Serial No. 195,007

'iClaima This invention relates to concrete structures. and in particular to a process of densifying and solidifying masses of concrete, such as, for example, piers, bridges, dams and the like.

When concrete structures of large mass are made they usually contain numerous voids. pockets, etc. After being exposed to weathering and aging, cracks frequently develop, so that the interior of the mass becomes more or less porous or honeycombed. Such a porous condition may be due to many causes, such as improper cement mixes, improper placement of the cement. seepage of water therethrough, freezing, and the like. Also, when large masses of concrete have been newly erected it frequently happens that the interior of the structure may have numerous voids, due to arching of the material, incomplete filling of the cement with nner particles around the aggregate, and improper placement of the concrete mix. The durability and life of such structures may be greatly prolonged, and the structure greatly strengthened, by filling in substantially completely the pockets, cracks, ssures, voids, and the like, in the structur, whether it be new or old.

It is an object of the present invention to provide a process for densifying and solidifying concrete structures, whether new or old.

Another object of the present invention is to provide a process for densifying and solidifying concrete structures which will eectively reach substantially all vof the structure under treatment.

' Other objects and advantages will become apparent from the following detailed description accompanied by the drawing, in which:

Figure 1 is a side elevation, with parts broken away, of a concrete structure treated according to the present invention; v

Fig. 2 is an enlarged sectional view of a portion of the grout nipple;

Figs. 3 and 4 are cross sections through a structure such as shown in Fig. 1, showing the method of treatment according to the present invention;

Fig. 5 is a cross section through a structure illustrating a region after treatment from one drilled hole; and

Fig. 6 is a diagrammatic view of the apparatus including the grout gun and grout nipple.

With reference to the accompanying drawing, in which like numerals refer to like parts throughout the several views, it may be seen that the present invention briefly may comprise, for example, the following steps:

A plurality of holes are formed, as by drilling, in the surface of the concrete mass to a suitable depth, such as two or three feet, and the loose concrete removed from the holes. The holes may be washed with water to ilush out any loose 5 material from the voids and cracks of the porous, honeycombed interior of the mass. Air under pressure is supplied to the holes to drive substantially all the washing liquid from the concrete mass. The repair material is next supplied to 10 the holes under pressure to force it into all the interstices, voids, fissures, etc. This is allowed to set for a sumcient length of time and then the process of drilling, washing, filling and setting is repeated, the drilling in each case being done for g5 suitable depth increment, such as two or three eet.

As seen in Fig. l, a plurality of holes I may be formed in any desired arrangement or locality in the structure 2, but, preferably, are disposed go in a predetermined pattern, so that substantially all of the structure will be treated by the process. It may be advantageous to drill the holes vertically, as in the case of a pier, or the holes may be made in a horizontal direction, an 25 example of this being in the vertical side wall of a bridge support. Arches and tunnels may also be treated, generally in a direction approximately normal to the surface. However, as previously described, it is preferable that an individual patau tern be laid out for each type of structure.

In order to bond the repair material and render it more effective, the holes are preferably washed or ushed out to displace any loose particles of material which may be present, due to u drilling, disintegration, or faulty construction of the concrete mass. The washing liquid is preferably water, and it is desirable that it be heated, since it will cleanse the concrete better and facilitate the bonding of the repair material to n the structure.

The admission of a gas. such as air under pressure, is to drive out substantially all the washing liquid from the porous concrete. It has been found advantageous to force the repair material 5 into the holes in the mass without iirst diminishing the gas pressure. 'Ihis may be carried out by the use of suitable apparatus, such as described below.

Apparatus which may be employed is shown o nected to the grout gun by a suitable pipe or u flexible hose line 6. Fig. 2 shows an enlarged view of the intrusion nozzle, which comprises a hollow pipe or conduit 'I having an outwardly extending flange l 'at the mouth end thereof. The pipe 1 is provided with external threads spaced a suitable distance from the mouth of the pipe to carry an annular threaded ring 9 having handles III. Adjacent the flange 8 is a rubber collar II loosely mounted on the exterior of the pipe, and adjacent the collar extending substantially to the ring 9 is a metallic sleeve I2 provided with an outwardly extending flange I3 adjacent the rubber collar and an outwardly extending flange I 4 adjacent the ring 9. By means of this arrangement the nozzle may -be inserted into an aperture, and by turning the handle I 0 the sleeve I2 will Ibe forced against the flexible collar II, thereby expanding the same into engagement with the walls of the drilled hole and anchoring the nozzle therein. When the nozzle is anchored in a hole, the repair material, supplied to the nozzle from th gun by air pressure, leaves the nozzle at its mouth end, inwardly of the anchored portion, and is forced into the voids, fissures and pockets which are in the region surrounding the hole into which the nozzle has been inserted.

Figs. 3, 4 and 5 show the structure at various steps in the treating and solidifying process. First, a hole is formed, as by drilling to a predetermined depth level in the structure, Aas shown in Fig. 3, then the nozzle 5 may be inserted and anchored therein. The hole may be flushed with washing liquid to displace the loose material, said liquid being supplied through a pipe or flexible hose line I5, preferably, after being heated by passage through a water heater I6 of any suitable type. Fig. 6 shows the repair material line 6 connected to the nozzle, but it may be seen that the water line I5 may be readily interchanged therewith. 'I'he lines 6 and I6 carry suitable couplings or fittings for attachment to or removal from the nozzle 5. A blast of compressed air may be admitted through the nozzle to force the washing liquid out of the structure, such compressed air being communicated to the nozzle from a suitable air compressor Il through a flexible pipe or hose line I8 adapted to be connected to the nozzle at a fitting I9, as shown in Fig. 6. In order to change the connection to that shown in Fig. 6 and admit repair material to the nozzle, a valve on the water line I5 may be closed, the line I5 disconnected from the nozzle and the hose or pipe line 6 connected to the nozzle. By opening a valve 55 2I on the line 6 and a valve 22 on the nozzle in front of the fitting I9 the repair material may be admitted from the gun 3 to the nozzle without first diminishing the air pressure and the repair material is forced through the nozzle into the region of the structure surrounding the hole.

To permit the repair material to remain in place until it has set and become rmly bonded to the structure it is preferable that the pressure which forced the repair material into the structure be maintained for a period of time after a sufficient amount of material has been forced into the structure. Accordingly, the valves 22 and 2| are provided on the nozzle and pipe line,- respectively, as shown in Fig. 6. The valve 22 is provided on the end of the nozzle, while the valve 2l is provided near the end of the hose line adjacent the nozzle, so that when they are closed the hose line may be disconnected from .the nozzle and removed for attachment' to other nozzles, and the 7a. nozzle may remain in the hole, maintaining pressure on the'repair material until the repair material has set as long as desired.

After the repair material has been allowed to set for a sufficient length of time the hole is drilled through a portion of the structure, which has just been filled, to the next depth level where the previously mentioned process may be repeated. Fig. 4 shows a portion of the structure as treated after a subsequent repetition of the process. The process of drilling, washing, filling and redrilling is continued until substantially the entire structure has been treated by this method. After one or more of the holes has been drilled and the region adjacent the hole has been treated to a suicient depth, the hole may be filled with the repair material to render the structure solid, as shown in Fig. 5.

'I'he pressure required to drive moisture out of the structure and also to force Athe repair material into the structure varies with the structure being treated. If the structure has relatively few voids .and air pockets, higher pressures are required to ll the interstices, although the amount of material needed is less, and it follows that with a structure containing a relatively large number of voids the required pressure is decreased and the required amount of repair material is increased. The pressures used vary from 50 to 500 pounds per square inch, depending on the specific job. For ordinary purposes a small capacity compressor will be satisfactory, and in case a pressure greater than approximately 125 pounds per square inch is normally necessary, an hydraulic compressor may be used to advantage. When a concrete structure being repaired requires a relatively high pressure, such as, for example, a pier which extends for some distance under the surface, it is often desirable to use a pump to aid in forcing repair material into the structure. Any suitable pump may be connected in the line 6 between the gun and the nozzle to insure that repair material is forced into the voids and interstices of the concrete structure.

In carrying out the present invention it is usually desirable that the repair material used lhave a relatively high plasticity and fluidity. In

this way pressure losses through the apparatus are reduced and the possibility of the material setting too rapidly and causing an obstruction in the apparatus is substantially eliminated. Also, the material is more susceptible of being forced thoroughly into the voids and interstices of the concrete mass, thereby densifying and solidifying the structure into a permanent durable unit.

An example of a repair material composition which has Ibeen found to have excellent characteristics for this process is a mixture of Portland cement, pulverized, hydraulically active material, such as, for example, blast furnace slag, a water repellent, oleaginous material, and water.

The proportions of the materials may be substantially varied, but a desirable composition is eight parts Portland cement, eight parts pulverized water-quenched, blast furnace slag, and one part oleaginous material comprising one or more animal or vegetable fatty substances, such as the fatty acid glycerldes, the fatty acids themselves, or the salts thereof. One suitable material is stearic acid itself or a derivative thereof. 'I'he oleaginous material such as stearic acid or stearin is mixed with Water and forms an emulsion into which the other ingredients may be thoroughly admixed. If desired, a relatively small amount of lime may be added which combines with the fat and aids in forming the emulsion. Sufficient water is'included in the mix to bring it to a desirable consistency, which is somewhat dependent upon the size and quantity of interstices of the structure being treated. Where the average size of the interstices is small the viscosity of the mix is preferably low and the viscosity may be increased as the average size of the interstices is found to increase.

Such a repair material as mentioned above has the property of keeping the cement and slag in suspension during its iiow through the hose and while it is being pumped under pressure into the cement structure, so that the tendency for the cement to separate is substantially minimized and the material, due to its ilowability, may readily be forced into the small cracks and interstices of the structure for substantial distances beyond the end of the nozzle. When set, the repair material does not shrink materially and, therefore,

keeps the voids and interstices filled preventing leakage through the structure.

The composition of the repair material is described and claimed in my co-pending application Serial No. 280,141, filed June 20, 1939.

After the interior of the structure has been densiiled and solidified it may be desirable that the surface of the structure be treated by a process which will render it impervious, so that moisture or some other substance deleterious to the concrete cannot gain access to the interior of the structure and cause deterioration. An illustration of such a process is one in which a suitable weatherproong composition is applied to the surface of the structure in any suitable manner and is thoroughly worked into the surface. It has been found that when a weatherprooilng composition is applied under pressure, and simultaneously rubbed into the concrete by means of an abrasive stone or an annular power driven carborundum wheel, all surface projections are removed and all surface voids are filled, thereby providing a structure having a smooth surface of uniform color which is in itself dense and durable to an appreciable thickness.

'Ihe process previously described herein may be applied to porous stratas or masses of earth, natural rock and the like as readily as it may be applied to concrete structures. Prior to the construction of a dam or other concrete structure it is often desirable to solidify the ground on which such structure is to be located in order to provide g a firm and impermeable foundation for the structure without removing the earth and/or rock.

By using the process of the present invention a solid and dense foundation and one which will be impervious to water may be had at great savings in cost.

Thus, it may be seen that according to my process a concrete structure may be solidified and densified, increasing both its length of useful life and strength. This process is equally applicable to old and new structures to render them substantially impervious to weathering and the like. The addition of repair material to the voids and pockets of a structure will also greatly increase its strength and, by making the structure solid and dense, it; will greatly increase its scribed, and the particular procedure set forth. are presented for purposes of explanation and illustration. and that various modifications can be made without departing from my invention as defined in the appended claims.

What I claim is:

1. .The process of solidifying and densifying a concrete mass, comprising forming a hole to a predetermined depth, washing loose material from said hole, forcing gas under pressure into said hole to displace the washing liquid, forcing repair material into the region of the concrete surrounding said hole, allowing said repair material to set, and repeating said sequence of operations at successively deeper levels of the mass.

2. The process of solidifying and densifying a concrete structure, comprising drilling a plurality of holes to a predetermined depth according to a predetermined pattern, forcing liquid under" pressure into said holes, forcing gas under pressure into said holes, forcing repair material 'through nozzles disposed in said holes into the region surrounding said holes to substantially fill the voids and interstices of the concrete mass communicating with the inner ends of said holes, holding said repair material in position under pressure until the repair material sets, and repeating such operations at successively deeper depths in the structure, whereby a solid concrete structure is formed having a minimum of porosity.

3. 'I'he process of solidifying and densifying a Aconcrete mass, comprising forming a hole to a predetermined depth, inserting a nozzle into said hole and anchoring the nozzle therein, forcing liquid under pressure into said hole, forcing gas under pressure into said hole to displace the liquid, forcing repair material through said nozzle into interstices communicating with said hole, allowing said repair material to set, and repeating said sequence of operations at successively deeper levels of the structure.

4. 'I'he process of densifying and solidifying a concrete structure, which comprises drilling a plurality of holes in a concrete structure to a relatively short predetermined depth, inserting nozzles in said holes, anchoring the nozzles in the holes, forcing repair material under pressure through the nozzles and into the concrete structure inwardly of the anchor, and adjacent the holes, withdrawing the nozzles, redrilling the holes to a further predetermined depth, and repeating said forcing and drilling operations to treat substantially all of the concrete structure. 5. 'I'he process of solidifying and densifying a, concrete mass, comprising forming a hole to a predetermined depth, inserting a nozzle in said hole, anchoring the nozzle therein, forcing repair material through said nozzle into the region around said hole, allowing said repair material to set, repeating said sequence of operations at respectively deeper levels of the structure, and applying weatherproof-lng material to the surface of the structure and thoroughly working the weatherproofing material into the surface, whereby an impervious, solid concrete structure is formed, having a minimum of porosity.

6. The process of solidifying and densifying a concrete mass, comprising forming a. hole to a. predetermined depth, washing loose material from said hole, forcing gas under pressure into said hole to displace the washing liquid, forcing repair material'into the region of the concrete surrounding said hole, allowing said repair material to set, repeating said sequence of operaworking the composition into the surface, where-v by an impervious solid concrete structure is formed, having a minimum oi' porosity.

7. 'I'he process of solidiiying and densiiying a concrete structure, which comprises forming a hole to a predetermined depth, anchoring a nozzle in said hole and sealing the hole adjacent the outer end thereoi, displacing the loose material of the concrete structure communicating with mum of porosity.

the hole. forcing repair material under pressure into the voids and interstices in the region oommunicating with said hole. permitting the repair material to set under pressure. withdrawing the nozzle, and continuing the operations at successive depth levels in continuations of the'hole and in additional holes according to a predetermined pattern in the concrete structure, whereby a solid concrete structure is formed having a mini- 

